Internal combustion engines have many moving parts, and a number of these parts slide against each other with very tight tolerances. As such, these parts require lubrication to allow them to slide against one another and prevent the parts from becoming damaged.
Lubrication of the pistons of the engine is particularly important. As the pistons reciprocate in the cylinders as many as several thousand times per minute, they slide against the cylinder walls. In addition, the connection between the piston and the control rod (known as the “wrist pin”) is subjected to sliding friction as the angle between the piston and the control rod changes throughout the engine cycle. It is important to deliver adequate lubricant to these sites, to ensure proper functioning of the engine.
A lubricant pump is typically employed to provide a regular supply of lubricant to these and other parts of the engine. The pump supplies lubricant simultaneously to suitable locations within the engine so that the lubricant reaches the sites where lubrication is required. For example, in a two-stroke engine, lubricant may be supplied to the air intake system of each cylinder, at a point upstream from the reed valve. The air intake system of the engine carries the lubricant into the combustion chamber of the cylinder, where it provides lubrication between the piston and the cylinder wall. Lubricant may also be provided to nozzles that are oriented to spray the lubricant on the wrist pin of each piston. The pump would supply lubricant to each of these locations, to ensure that they remain lubricated.
However, prior art pumps have a number of drawbacks. Pumps typically include check valves to ensure that the lubricant is pumped in the intended direction, toward the surfaces that require lubrication, and to restrict the flow of lubricant in the opposite direction. These check valves are susceptible to sticking at cold temperatures, resulting in irregular or insufficient supply of lubricant. In addition, lubricant must be supplied to a number of areas at the same time, particularly in engines having several cylinders, each with a piston requiring lubrication. For example, if the engine has four cylinders, the pump must supply lubricant to eight separate locations: four pistons and four wrist pins. Pumping lubricant to eight places simultaneously reduces the quantity of lubricant that can be supplied to each location, and thereby reduces the effectiveness of the lubrication.
Therefore, there is a need for a way of providing lubrication to portions of an engine.